A Fishy-Looking Test Score Distribution

Jan 7, 2014 · 3,329 views

Every spring, 12th graders in India nervously sit to take board exams. Passing these exams will earn them the Indian equivalent of a diploma; their specific scores could make or break hopes for scholarships, college admissions, and employment.

Because these tests are standardized, multiple-choice affairs, a fair assumption to hold is that there won’t be evidence of foul play in grading. But, as a recent scores analysis discovered, there are indeed some strange things going on:

The graph above shows the distribution of scores on the 2013 CBSE biology test. The CBSE is the most widely-administered board exam in India. Notice the two funny humps. The first one seems charitable enough- a relatively high number of students receive scores between 55% and 60%, just enough to pass. The folks grading these tests are bumping up failing scores so that borderline students can pass. This isn’t anything too farfetched; exam graders in Poland appear to be doing the same thing.

There is second hump in the graph. More students receive a 95% than any other score on the test. By a long shot. According to Dr. Glenn Rowley of the Australian Council for Educational Research, these scores “bear no resemblance to any known distribution, and defy explanation.”

The 95% spike is a recent development, whereas giving students a courtesy pass has historical precedent. Here’s a graph of the scores for the same biology test in 2008:

The 2008 histogram resembles a pretty normal distribution, except for the friendly grading at 55%. There is no second hump whatsoever at the 95% mark. The same historical trends exist across multiple other CBSE subject tests, which paints a picture of widespread score tampering on board examinations.

The motivation to fudge scores seems clear enough. The pressure to earn high scores on these tests is extremely high in a country where 68% of the population lives on under $US 2.00 per day. India is also home to the world’s largest population of teenagers, many of whom fiercely vie for highly coveted scholarships, jobs, and admissions to universities.

Regardless of intent, the high stakes nature of standardized tests in India has led to serious misconduct. However, the United States (the patron saint of the multiple-choice test) is not devoid of exam corruption; a handful of educators in Atlanta recently pleaded guilty to their role in a score-tampering scandal.